How to downgrade MacOS Monterey to macOS Big Sur

Downgrade Prerequisites

• A full backup of your Mac before installing MacOS Monterey (from Big Sur, etc.)
• A bootable macOS Big Sur installation drive for easy reinstallation Installing macOS (for Apple Silicon Macs)
• Active Internet Connection

Please note that for Apple Silicon Macs you can only downgrade to macOS Big Sur because this is Big Sur The earliest supported version. The latest M1 Max and M1 Pro Macs cannot be downgraded from Monterey.

How to Downgrade MacOS Monterey to Big Sur

Always perform a full Time Machine backup before proceeding. Also, make sure you have an older Time Machine backup before updating to MacOS Monterey.

Please note that any data differences between the two backups must be resolved manually by copying the files created between Monterey and the previous macOS backup to something like an external hard drive so that they can be Restore them after downgrading.

Downgrading involves erasing your Mac, reinstalling macOS, and then restoring from Time Machine.

1. 1. Restart your Mac and do the following based on your Mac architecture
      • For M1 Mac: Now hold down the power button until you see the startup options, then select " Options" and continue
      • For Intel Mac: Immediately hold down the Command R key to boot your Mac into recovery mode
   2. Now in recovery mode, select "Disk" from the options Tools"
   3. Select the drive where macOS Monterey is installed and select "Erase" from the options - this will delete all data on your Mac
   4. Select "Apple File System (APFS)" ( most likely) or "Mac OS Extended Journaled (HFS)" (usually older Macs without SSD drives) as the file system type and click "Erase" to format the data on your Mac THIS ERASES ALL drive , this is why it is important to have a backup of your data available
   5. Exit Disk Utility after drive erasure is complete
      • For Intel Mac, from the macOS Utilities menu Select Recover from Time Machine
      • Select the Time Machine drive connected to your Mac and select Continue, then on the Select a Backup screen, select the most recent backup that was made with the macOS version you want to downgrade to
      • Click "Restore" to start restoring/downgrading to this version of macOS
   6. • ##For Apple Silicon M1 Mac: * * Restart your Mac and boot from the macOS Big Sur Installer USB drive by connecting the USB Installer to your Mac and holding down the power button to select macOS Installer from the boot menu
      On your Mac select Reinstall macOS Big Sur" and complete the installation steps
      • macOS Big Sur Once the installation is complete, you will be taken to the typical Mac setup screen, where you can choose to restore from a Time Machine backup, select the macOS Big Sur Time you want to restore from Machine backup and proceed as usual

* Please note that if you are trying to boot an Intel Mac using a bootable USB drive, you may need to allow Boot external drive on chip Mac.

** You can also reinstall macOS Big Sur on an Apple Silicon Mac using Internet Recovery, accessible from the boot menu option by holding down the power button during system startup. Depending on the speed of your internet connection, this may be slower than using a USB key.

When everything is complete, you will be restored to macOS Big Sur.

Now is the time to resolve any file differences, so if you have data that was manually backed up between the Monterey update and the restored Big Sur backup, you will need to copy those files.

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